mirror of
https://github.com/facebook/react-native.git
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Samuel SuslaandFacebook GitHub Bot
5fa6c5a941
Summary: changelog: [internal] You can read more about this rule on https://clang.llvm.org/extra/clang-tidy/checks/modernize-pass-by-value.html # Isn't it wasteful to copy? Isn't reference more efficient? This rule of thumb is no longer true since C++11 with move semantics. Let's look at some examples. # Option one ``` class TextHolder { public: TextBox(std::string const &text) : text_(text) {} private: std::string text_; }; ``` By using reference here, we prevent the caller from using rvalue to and avoiding copy. Regardless of what the caller passes in, copy always happens. # Option two ``` class TextHolder { public: TextBox(std::string const &text) : text_(text) {} TextBox(std::string &&text) : text_(std::move(text)) {} private: std::string text_; }; ``` Here, we provide two constructors, one for const reference and one for rvalue reference. This gives the caller option to avoid copy. But now we have two constructors, which is not ideal. # Option three (what we do in this diff) ``` class TextHolder { public: TextBox(std::string text) : text_(std::move(text)) {} private: std::string text_; }; ``` Here, the caller has option to avoid copy and we only have single constructor. Reviewed By: fkgozali, JoshuaGross Differential Revision: D33276841 fbshipit-source-id: 619d5123d2e28937b22874650366629f24f20a63
60 lines
1.7 KiB
C++
60 lines
1.7 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#pragma once
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#include <memory>
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#include <react/renderer/componentregistry/ComponentDescriptorRegistry.h>
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#include <react/renderer/core/ComponentDescriptor.h>
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#include <react/renderer/core/ShadowNode.h>
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#include <react/renderer/core/ShadowNodeFamilyFragment.h>
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#include <react/renderer/core/ShadowNodeFragment.h>
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#include <react/renderer/element/Element.h>
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#include <react/renderer/element/ElementFragment.h>
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namespace facebook {
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namespace react {
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/*
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* Build `ShadowNode` trees with a given given `Element` trees.
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*/
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class ComponentBuilder final {
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public:
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ComponentBuilder(
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ComponentDescriptorRegistry::Shared componentDescriptorRegistry);
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/*
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* Copyable and movable.
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*/
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ComponentBuilder(ComponentBuilder const &componentBuilder) = default;
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ComponentBuilder(ComponentBuilder &&componentBuilder) noexcept = default;
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ComponentBuilder &operator=(ComponentBuilder const &other) = default;
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ComponentBuilder &operator=(ComponentBuilder &&other) = default;
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/*
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* Builds a `ShadowNode` tree with given `Element` tree using stored
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* `ComponentDescriptorRegistry`.
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*/
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template <typename ShadowNodeT>
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std::shared_ptr<ShadowNodeT> build(Element<ShadowNodeT> element) const {
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return std::static_pointer_cast<ShadowNodeT>(build(element.fragment_));
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}
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private:
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/*
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* Internal, type-erased version of `build`.
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*/
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ShadowNode::Unshared build(ElementFragment const &elementFragment) const;
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ComponentDescriptorRegistry::Shared componentDescriptorRegistry_;
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};
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} // namespace react
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} // namespace facebook
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